High solids content elastomer-based aerosol spray adhesive



Sept. 3, 1968 v KREMER ET AL HIGH SOLIDS CONTENT ELASTOMER-BASED AEROSOLSPRAY ADHESIVE Filed March 17, 1967 fikw \Q kmukmu bmwwg a CONTENT OF6245701145? K 5 WWW MW mam m Wm United States Patent 3.400.095 HIGHSOLIDS CONTENT ELASTOMER-BASED AEROSOL SPRAY ADHESIVE Leon V. Kremer,Cottage Grove Township, Washington County, and George M. Rambosek,Maplewood Village, Minn., assignors to Minnesota Mining andMannfacturing Company, St. Paul, Minn., a corporation of DelawareContinuation-impart of application Ser. No. 453,825,

May 6, 1965. This application Mar. 17, 1967, Ser.

4 Claims. (Cl. 26032.8)

ABSTRACT OF THE DISCLOSURE Aerosol packaged spray adhesives including a10-35% by weight dispersion of crosslinked dispersed insoluble highstrength milled rubbery polymer in organic liquid together withtackifier resin and a small amount of soluble elastomer which sprayswithout forming rubbery strings or nonadherent mist.

This application is a continuation-in-part of our copending applicationSer. No. 453,825, filed May 6, 1965, now abandoned.

This invention relates generally to aerosol packaged adhesives. Moreparticularly, the invention relates to aerosol packaged high solidscontent adhesives having a high elastomer content.

There has been a considerable demand for high strength aerosol packagedadhesives which can be sprayed on materials such as paper, cardboard,cloth, or foamed plastics. Prior to the present invention, suchadhesives which provided good resistance to shear and peel containedless than about 5% by weight elastomeric material. The low solidscontents at which such adhesives are conventionally packaged are notonly wasteful of solvent and propellant, but result in a thin spray inwhich the volatiles soak into porous substrates. As a result, substratessuch as paper are made translucent by the volatile liquids and otherfragile objects tend to be otherwise injured by the solvents used. -Inorder to provide aerosol adhesives having a reasonably high solidscontent it has often {been attempted to add an inert solid filler.However, compositions containing such fillers do not provide the desiredhigh strength adhesive bonds. When it was attempted to add elastomericmaterials to the adhesives it was found that the materials would gum upand flow out of the containerin rubbery strings rather than as a usablespray. It was also found that elastomeric materials agglomerated withinthe container into a semisolid mass or irreversibly separated into twoor more phases, thus rendering the material unsprayable.

Highly cross-linked or gelled elastomers have been known inv theadhesives art for some time: see for example Stevens U. S. Patent No.2,673,845, granted Mar. 30, 1954. Previous to this, lFinn Patent No.2,537,982, granted Jan. 16, 1951, concerned self-toughening adhesivecements comprising elastomers such as copolymers of butadiene andacrylonitrile. :Finn also observes that theretofore rubberybutadiene-acrylonitrile polymers had been vulcanized in adhesivecompositions, and discusses the diificulties or problems in respectthereto. More recently, Hendricks et al., Canadian Patent No. 586,489,issued Nov. 3, 1959, based on a United States filing date of Apr. 18,1955, discloses adhesive cement compositions containing highlycross-linked elastomers for general spray applications. However, none ofthese earlier efforts con- 'cerned themselves with the specific problemsof providing elastomeric based adhesives, .at high solids content,(e.g., above about percent) in areosol containers which can "ice bestored for long periods and sprayed without stringing out or cob-webbingon the one hand, or unduly misting, on the other hand. Insofar as we areaware, no one, prior to the present invention has practically orcommercially provided such a high strength elastomer-based areosolpackaged adhesive.

The present invention has overcome the ditficulties of the prior art byproviding an aerosol packaged elastomeric adhesive containing a highsolids content, i.e., between about 10 and 35 percent by weight of thecontents of the container. The solid component of the adhesives of thepresent invention contain a substantial amount of dispersed insolubleelastomeric material generally ranging from 5% to 25% of the weight ofthe contents of the container. The compositions of the present inventionremain sprayable for an extended period of many months or years,requiring at most only slight shaking by hand of the container toredisperse the contents. It has been 'found that the desired results areachieved by providing the r-ubbery polymer in the form of smalldispersed insoluble particles combined with a small, but significant,amount of soluble elastomer. The insoluble particles should range insize from at least large enough to be discrete insoluble (thoughswelled) particles of colloidal size in the carrier liquid up to largerparticles which either remain suspended in the carrier liquid for aconsidera-ble period of time after mixing of the ingredients or can beredispersed and remain so for minutes or hours after agitation, e.g., byhand shaking. In commercial practice it is preferred to screen outparticles larger than about 150 microns from the dispersion in order toremove material which would settle out in the container and/or plug thenozzle.

The preferred embodiments of the present invention incorporate abalanced proportion of such insoluble particles in combination with atackifier resin and a small amount of elastomer which is soluble in thecarrier liquid. The soluble elastomer must constitute between 0.3 and 3%by weight of the total contents of the container. It has been found thatif less than 0.3% soluble rubber is present, the composition will sprayout as an unusuable mist. On the other hand, if more than 3% solublerubber is present, the composition will spray out as rubbery strings. Ithas been discovered that a small but important amount of solubleelastomer must be present in addition to the insoluble elastomer andtackifier resin. Without the soluble material the compositions form anonadherent mist. As will be more fully explained hereinafter,

if more highly gelled (i.e., insoluble) rubbers are used, the percentageof total elastomer in the container must be increased in order toprovide the required amount of soluble elastomer in the adhesive.

In the drawings, FIGURE 1 is a graph showing the useful compositions interms of percentage of ingredients in the container at different gelcontents.

Referring more particularly to the drawings, the percentages based onthe total container contents of insoluble elastomer and solubleelastomer are plotted for different gel contents. Ge] content is definedas the percentage of insoluble elastomer in a particular elastomersample when dissolution is attempted in a good organic solvent. As seenfrom the curves, the amount of soluble elastomer which can be present inthe container, indicated by area 10 on the graph, remains substantiallyconstant for elastomers of different gel content. In order to maintainthe required amount of soluble elastomer, the amount of insolubleelastomer, presented by area 12 on the graph, must be progressivelyincreased as the gel content of the elastomer increases.

The minimum gel content which has been found useful is about 60%,because at gel contents below about 60% the total elastomer content inthe container becomes too low so that the high solids content product ofthis invention is no longer obtained. The maximum gel content whichappears to be useful is about 97%. At gel contents above this amount,the elastomer content in the container must be increased in order toprovide the required amount of soluble elastomer to such a high amountthat the contents of the container will no longer readily spray throughan orifice, but will rather fiow out as a solid stream or squirt in themanner resulting from a common toy squirt gun. Thus elastomers havinggel contents from about 60 to 97% are useful, and the amounts used inthe container must be varied in accordance with the accompanying graphsin order to provide a relatively constant small amount of solubleelastomer. This amount of soluble material may be varied from about 0.3to about 3% of the contents of the container in order to provide ausefully sprayable adhesive.

Various types of aerosol containers, such as are known to those skilledin the art, can be used in practicing the invention. Conventionaltin-plated cans will generally sufiice, but if the adhesive compositioncontains ingredients reactive with the metal of the containers, the sameshould be coated on their inner surfaces with a stable polymeric coatingsuch as a vinyl or an epoxy polymer in order to minimize any deleteriousinteraction between the adhesive composition and the container. Theaerosol container preferably is of the type in which the propellant isin liquefied form and mixed with the adhesive composition. As the streamof adhesive and liquefied propellant is dispensed from the orifice inthe nozzle of the aerosol container, the propellant vaporizessubstantially instantaneously, thereby breaking up the stream intoairborne particles of the desired size. The pressures used generallyrange between 25 and 45 p.s.i.g., the latter limit being imposed forreasons of safety during shipment and storage. About 35 p.s.i.g.pressure in the container is generally preferred.

Conventional pressure-liquefiable, normally gaseous propellants such aspropane, carbon dioxide and commercial Freon can be used in connectionwith the invention. In the container the propellant is present (beingusually charged) in liquefied form. Since it generally is mixed with theadhesive composition, the propellant should be of a type which will notinteract with the packaged adhesive in such a manner that the adhesiveproperties will be adversely affected. The liquefied propellant in suchcases will become part of the solvent system in the container, and someingredients of propellant systems such as methylene chloride,conventionally used as a vapor pressure depressant for liquefiedpropellants will also exhibit a solvating effect on the materialsdissolved and suspended in the liquid in the container. This in someinstances may be advantageous.

The principal ingredients of the adhesive compositions of the presentinvention are a rubbery elastomeric composition and a carrier liquidtherefor in which the elastomer is substantially insoluble. It is oftendesirable to add substantial amounts of tackifier resins in order toimprove the adhesive properties of the composition, and if desired, suchingredients as viscosity stabilizers and antioxidants in minor amounts.Tackifier resins are known to those skilled in the art; see, forexample, U. S. Patent 3,239,478 (Harlan) issued Mar. 8, 1966.

The solvent or carrier liquid is generally selected on the basis of theend use requirements, solvent properties and compatability with theadhesive components. The liquid should be such that it will notdissolve, discolor or otherwise harm the substrates on which theadhesive is to be applied. Examples of suitable organic liquids includehexane, methyl ethyl ketone, methyl isobutyl ketone, and variousalcohols. The solvent properties of the liquid should be such that theelastomeric composition used is dispersible therein while the resinousand stabilizing components, if any, are soluble therein.

A wide variety of elastomeric materials can be used in practicing theinvention. The preferred compositions are highly cross-linked additionpolymers, such as butadiene styrene, butadiene acrylonitrile andpolychloroprene rubbers. Conventional cross-linking agents such asdivinyl benzene or the equivalent are preferred. Furthercross-linkingagents for diene rubbers are listed in U. S. Patent No.2,673,845, aforesaid. Other cross-linked rubbers having the required gelcontent, such as polyurethanes, polysulphide rubbers, etc., may also beused.

It is possible to place the elastomeric material in suspension in theorganic carrier liquid by a number of methods. For example, a latex canbe coagulated, dried, and broken down, e.g., by milling, and then takenup in the organic system. Or, the aqueous latex suspension can beconverted to an organic suspension by employing extraction ordistillation techniques as generally shown in Hendricks et 211.,Canadian Patent No. 586,489. Due regard in either of these methodsshould, of course, be given to the milling in accordance with theteachings herein so as to render it useful in the aerosol packagedelastomeric adhesives of the present invention. Generally latexpolymerized rubbers are cross-linked to such a high degree thatadditional soluble rubber must be added separately.

It is preferred to use dry polymers which must be milled beforedispersion in the carrier liquid. The dry polymers have the advantagethat the absence of water in the system minimizes corrosion and otherdeleterious side reactions of the adhesive compositions. Moreover, thedry polymers are generally washed to eliminate impurities such assurfactant, stablizers, etc., present from the polymerization process.The absence of these impurities provides somewhat better adhesivequalities. Greater freedom in compounding is also possible since thechoice of solvents, and consequently the resins soluble therein, is notlimited as in the case of dispersions obtained by solvent extractionprocesses in which only a limited number of solvents are operative.

The invention will be further explained with reference to the followingnonlimitative examples. All parts given are by weight unless otherwisenoted.

Example I A base polymer was prepared by milling in an 84 inch rubbermill the following elastomeric polymers starting from slab form:

.The mill was set to operate with a gap between the rolls of 0.110 inchand a friction ratio of 1.25 to 1.00 (i.e., one of the rolls was rotatedat a speed 1.25 times the speed of the other roll). The milling wascontinued for about 2 /2 minutes during which time the temperature ofthe material was kept in the temperature range of 80 F. to F.

The milling conditions just specified, while suitable for the particularbatch of elastomer used, are somewhat approximate. In order to obtainoptimum spray qualities and to contend with variations in propertiesoccurring among different batches of commercially available materials,we prefer at this point to run the following test: In order to determinethe exact milling conditions required to obtain optimum spraycharacteristics from a particular stock it has beenfound desirable toprepare an aliquot portion of the adhesive formulation given belowleaving out the methylene chloride and a portion of the hexane to testthe spray-ability thereof, for example, by spraying through a low airvolume spray gun such as the De Vilbiss P-CGA- 501FF. In carrying outthis test, a laboratory sized quantity of the elastomer is prepared on alaboratory rubber mill, and any high shear type laboratory mixingequipment can be used to prepare the adhesive. Only sufficient hexane toreduce the viscosity to 2000 centipoises should be added. It has beenfound that formulations which spray satisfactorily on a vertical surface24 inches distant from the nozzle at 20002300 oentipoises using the lowair volume equipment will spray satisfactorily from an aerosolcontainer. If stringing or cob-webbing occurs, this is an indicationthat too much soluble elastomer is present. The amount of soluble rubberis preferably reduced by reducing the mill time to a minimum of 2minutes while holding other variables constant. If reducing the milltime to 2 minutes does not eliminate the cob-webbing, the milled productshould be allowed to stand for l to 4 days at room temperature to permitthe product to cross-link again into insoluble rubber. If, on the otherhand, excessive misting occurs, this is an indication that theproportion of insoluble rubber is too high. In this event the mill timeis increased to further reduce the particle size and break more of therubber down into soluble elastomer until a sprayable mixture isproduced.

The adhesive formulation into which the prepared elastomer isincorporated is as follows:

Parts by weight Milled base elastomer 100 80% dimeric pine wood resinacids; monomen'c pine wood resin acids and neutral material (Dymerexresin) 100 Glycerol ester of hydrogenated rosin (Stabalite Ester #10) 40Antioxidant (mixture of octylated diphenyl amines, Agerite Stalite) 2Morpholine (a viscosity stabilizer) 1 Hexane 450-500 Methylene chlorideAll of the materials except the methylene chloride and a portion of thehexane were mixed in a high shear Struthers-Wells mixer until a smoothuniform mixture was produced. The methylene chloride was added whilemixing was continued and the viscosity of the resulting mixture wasadjusted to 700 centipoises by adding further hexane. The resinouscomponents dissolved in the hexane while most of the elastomericcomponents were present in the form of dispersed, insoluble gelledparticles.

90 parts of this mixture were charged into a tin plated aerosol can. Thecan was purged of air. The valve assemblies (Newman Green B-14-10) wereput into place and crirnped onto the can, 15 parts propane propellantwere forced through the valve to pressurize the can. Newman Green13-20-20 actuators were placed over the valves. These actuators wereprovided with orifices 0.018 inch in diameter. The mixture in the cancontained ap proximately 2 6% solids and was under a gauge pressure of35 psi. at 70 F. The adhesive sprayed well from the aerosol containerwithout cob-webbing or excessive misting, When sprayed on poroussubstrates such as styrofoam the adhesive coated the surface withoutseriously wetting the substrate with a uniform, tacky, rubbery coating.The adhesive did not Wrinkle paper when sprayed thereon.

In contrast with previous attempts to package elastomeric adhesives ofhigh elastomer content in an aerosol container the composition of thepresent example was remarkably stable even after standing for anextended length of time. The contents did not agglomerate and thematerial remained in a sprayable form, requiring only slight shaking byhand of the container to redisperse the contents.

6 EXAMPLE II Parts by weight A butadiene-acrylonitrile polymercrosslinked with divinyl benzene and polymerized to containapproximately 31% bound acrylonitrile (FR-N-1310) The polymer was milledon a 16 inch laboratory rubber mill set to operate with a gap betweenthe rolls of 0.05 inch and a friction ratio of 1.33 to 1. The millingwas continued for 10 minutes during which time the temperature of theelastomer was limited to a maximum of about F. by cold water cooling themill. The milled elastomer was blended with the remainder of theingredients in a high shear mixer until smooth and uni form, Theviscosity was reduced to 2000 c.p.s. by dilution with methyl ethylket-one.

90 parts of this mixture and 15 parts of dichlorodifiuoro methanepropellant (sold commercially as Freon 12) were packaged in anepoxy-lined aerosol container using the procedure of Example 1. Themixture in the aerosol can contained approximately 20% solids andapproximately 9% elastomer by weight and was pressurized at a gaugepressure of 35 p.s.i.g. at 70 F. The adhesive sprayed from the aerosolcontainer with a uniform, smooth pattern of high adhesive strengthwithout stringing, squirt ing, or excessive misting. As in Example I,the adhesive could be sprayed onto porous surfaces such as paper withoutwrinkling or excessive wetting.

EXAMPLE III Parts by weight Dried, milled, cross-linked polychloropreneelast- The above adhesive composition was prepared by coagulating theNeoprene 572 latex with acetone and drying for 60 hours at 120 F. Thedried polymer and the Neoprene AF were milled together on the laboratoryrubber mill set to operate as in Example H for 20 minutes Thetemperature of the elastomer in the mill reached a maximum of about F. Apremix was then made by reacting the CKR 1634, magnesia and water in thetoluol in a Kady Mill (sold by Kinetic Dispersion Corporation) at F. for30 minutes. The mill base and premix were then blended with thepetrobenzol and acetone in a high shear mixer until smooth and uniformlydispersed. The viscosity was reduced to 350 c.p.s. with a liquid carriercontaining a 3:2 ratio of petrobenzol/acetone.

100 parts of the mixture, 50 parts of methylene chloride, and 50 partsof dichloro-difluoro methane (sold commercially as Freon 12) werecharged into an epoxylined aerosol container in accordance with theprocedure set forth in Example I. The contents of the aerosol containercontained approximately 12.5% solids and approximately 7.7% dispersedinsoluble polychloroprene elastomer. The internal pressure of thecontainer was approximately 31 p.s.i.g. at 70 F. The adhesive sprayedfrom the container with a smooth, uniform pattern, without stringing,squirting, or cob-webbing. As in Example I, the adhesive could besprayed onto porous surfaces without excessive soak-in and the adhesiveproperties of the product were not measurably impaired by aerosolpackaging.

EXAMPLE IV Parts by weight Rubber 350 Dymerex resin (see Example I) 245Stabalite ester #10 (see Example I) 245 Morpholine 3.5 Antioxidant(Agerite Stalite-see Example I) 7.0 Hexane about 1300 The rubber wasmilled on a 16-inch laboratory mill set to operate with a gap betweenthe rolls of 0.05 inch and a friction ratio of 1.33 to 1. The millingwas continued for two minutes in each instance, during which time thetemperature of the elastomer was limited to a maximum of about 120 F. bycooling the rolls with cold water. The milled elastomer was blended withthe remainder of the ingredients in a high shear mixer until smooth anduniform. The viscosity was reduced to about 2,000 cps. by dilution withhexane. The amout of hexane used in each instance was varied to providethe solids content reported in each instance in Table No. 1.

A series of butadiene-styrene rubbers varying in gel content was used toprovide a series of samples having 93, 85, 83 and 74% gel content.Adhesive formulations were prepared from each of these rubbers inaccordance with the above formulation, at a series of solids contentsachieved by varying the amount of hexane in the mixture.

60 parts of the adhesive mixture and 10 parts of propane propellant werepackaged in glass bottle aerosol containers and pressurized as inExample I. The results obtained in attempting to spray these samples aretabulated in Table No. l. The data is also shown graphically in FIGURE 1of the drawings. Gel contents were determined by measuring solubility ofthe SBR rubber in toluene.

adhesive formulation as set forth in Example I. These include the amountof cross-linking of the rubber, the mill setting or distance between therolls, the amount of cross-blending, and the mill temperature. Theproportions of ingredients used in Example I above provide aparticularly suitable range of small to large size colloidal particles.If stringing occurs due to the presence of too much soluble material,the proportion of cross-linked insoluble particles can be increased byincreasing the proportion of the elastomer more highly cross-linked withdivinyl benzene. If misting becomes a problem, the proportion of thiselastomer should be reduced. Stringing and cob-webbing can also bereduced by reducing the mill time or the amount of cross-blending of thebase elastomer during milling, or alternatively, the milling temperaturecan be increased to a limit of 300 F. and preferably below 250 F. Ingeneral any change in processing which increases the proportion ofsoluble elastomer will increase the tendency toward stringing orcob-webhing of the spray and decrease the tendency toward misting whieany change in processing in which tends to increase the particle size orthe proportion of insoluble elastomer will increase the tendency towardmisting and decrease the tendency toward stringing or cob-webbing. Itwill be understood that complete elimination of the formation of anonadherent mist is not generally possible; however, excellent resultscan be achieved when no more than a small minor proportion of the sprayis formed into a nonadherent mist.

By good sprayability is meant in addition to the absence of cob-webbingor excessive misting that the adhesive when sprayed on a substrate 8" to10 from the nozzle will be deposited in a pattern at least one inchwide. The deposited adhesive will be in the form of a uniform continuouscoating. The sprayed adhesive coating will not, probably due to the highsolid content thereof, soak into porous substrates.

We claim:

1. A high solid content elastomeric based spray adhesive packaged underpressure, comprising a volatile organic carrier liquid; said liquidcontaining therein at least about 10% by weight solids including atackifier resin dissolved in said carrier liquid and a milledelastomeric addition polymer from which impurities such as surfactantshave been washed in the form of insoluble TABLE 1 Gel Solids SolidsSoluble content of content, content rubber Pressure in Observationrubber, percent of (percent of (percent of total container, percentadhesive container container p.s.i.

contents) contents) 12.0 10. 3 0. 42 Mist, soaked paper. 15. 0 12.9 0.5325 Do. 18.0 15. 4 0. 64 28 Do. 21. 0 18. 0 0. 74 29 Do. 24. 0 20. 6 0.84 30 Do. 27.0 23.1 0. 95 30 Do. 30.0 25. 7 1. 0G 33 Do. 33. 0 28. 3 1.17 38 Fair, some mist. 36.0 30. 9 1.27 39 Good. 38. 5 33. 0 1. 36 39Fair, bubbles in co g. 12.0 10.3 47 27 Misty, soaks paper. 15.0 12.9 .5827 Do. 18.0 15. 4 32 Do. 21. 0 18. 0 82 33 D0. 24. 0 20.6 93 36 Good.27.0 23.1 1.05 36 Do. 30.0 25. 7 1.16 36 Do. as. 0 28. 3 1.28 38 Fair.37. 8 32. 4 1. 47 39 Squirts. 12.0 10.3 .85 26 Misty, soaks paper. 15. 012. 9 1. 06 27 Do. 18.0 15. 4 1. 27 28 Do. 21. 0 18.0 1. 48 34 Good. 24.0 20. 6 1. 70 36 I Do. 27. 0 23. l 1. 36 Fair. 30.0 25. 7 2. 12 36Squirts. 33.0 28.3 2. 33 38 Do. 41. 6 35. 7 2. 94 38 Do.

In the case of dried and milled elastomers of the type set forth inExamples I-III, several variables can be controlled in addition to thelength of mill time and the age elastomeric particles less than aboutmicrons in size dispersably suspended in said carrier liquid; saidelastomeric polymer forming 5% to 25% by weight of said of the milledelastomer at the time it is mixed into the 7 adhesive and having a gelcontent of about 60% to 97%,

said adhesive containing from about 0.3 to 3% soluble elastom'er, saidelastomeric particles and said carrier liquid being contained in anaerosol container under pressure with a propellant which will cause saiddispersion to spray when discharged from said container through anorifice without forming more than minor proportions of nonadherent mistand without forming rubbery strings.

2. An aerosol packaged adhesive which will spray Without forming morethan minor proportions of nonadherent mist and without forming rubberystrings comprising a sealed, pressurized container coated on its insidesurfaces with a composition inert to the contents of the container, saidcontainer having an orifice for dispensing the contents, said orificenormally being closed; a means for opening said orifice to discharge thecontents; a sprayable adhesive composition contained within saidcontainer comprising a volatile organic carrier liquid containing atackifier resin dissolved therein, and a milled highly cross-linkedrubbery addition polymer from which impurities such as surfactants havebeen washed, said polymer being insoluble in said carrier liquid in theform of insoluble particles dispersed in said carrier liquid; saidrubbery polymer having a gel content of about 60% to 97%, said adhesivecomposition containing about 0.3 to 3% dissolved elastomers; a volatileorganic propellant under a pressure of about 25 to 35 pounds per squareinch contained in said container and being capable of volatilizing tobreak up said carrier liquid and the particles dissolved and dispersedtherein into a spray upon opening of said orifice, said elastomericmaterial forming 5% to 25% of the contents of said container.

3. The article of claim 2 wherein said rubbery polymer comprises abutadiene-styrene polymer formed from approximately 72 parts butadieneand 27 parts styrene crosslinked by approximately 0.7 part divinylbenzene.

4. The article of claim 3 wherein the solid material comprises between10% and 35% by weight of the contents of said container.

References Cited UNlTED STATES PATENTS 2,766,157 10/1956 Peterson26033.8 2,884,400 4/1959 Moore 26033.6 3,332,903 7/1967 Kavalir 260-32.8

FOREIGN PATENTS 586,489 11/1959 Canada.

MORRIS LIEBMAN, Primary Examiner.

L. T. JACOBS, Assistant Examiner.

PO-IOSO Patent No.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dated September 3,1968 end the: eeid Letters Petent ere hereby corrected It 11: certifiedthe: error eppeere 1n the above-identified patent In Column columnColumn 2,

column Column- 4,

Column 7,

Column 8,

Column 9,

column ee shown below:

1, line 21, "nonadherent" should read non-adherent l, line 52,"semisolid" should read semi-solid. line 18, redisperse" should readIce-disperse 2, line 47, "nonadherent" should read non-adherent line 40,"nonlimitative" should read non-limitative in "Table 1'', second columnheading ("Solids adhesive"), the word formulation should be insertedunderneath the word "adhesive".

lines 26 and 29, each occurrence of "nonadherent" should readnon-adherent line'7, "nonadherent" should read non-adherent and 9, lines22 and 25, each occurrence of the semicolon should be changed to a commaSIGNED AND SEALED mm: x. 801mm. 8. Commissioner 01 Pam J

